Hi Shuah, On Thu, Jan 24, 2019 at 01:32:37PM -0700, Shuah Khan wrote: > Media Device Allocator API to allows multiple drivers share a media device. > This API solves a very common use-case for media devices where one physical > device (an USB stick) provides both audio and video. When such media device > exposes a standard USB Audio class, a proprietary Video class, two or more > independent drivers will share a single physical USB bridge. In such cases, > it is necessary to coordinate access to the shared resource. > > Using this API, drivers can allocate a media device with the shared struct > device as the key. Once the media device is allocated by a driver, other > drivers can get a reference to it. The media device is released when all > the references are released. Thanks for the update. I have to apologise I haven't ended up reviewing the set for some time. After taking a look at the current version, I'm happy to see that a number of issues recognised during earlier review rounds have been addressed. Would you happen to have a media graph (media-ctl --print-dot and media-ctl -p) from the device? That'd help understanding the device a bit better for those who are not familiar with it. > > - This patch series is tested on 5.0-rc3 and addresses comments on > v9 series from Hans Verkuil. > - v9 was tested on 4.20-rc6. > - Tested sharing resources with kaffeine, vlc, xawtv, tvtime, and > arecord. When analog is streaming, digital and audio user-space > applications detect that the tuner is busy and exit. When digital > is streaming, analog and audio applications detect that the tuner is > busy and exit. When arecord is owns the tuner, digital and analog > detect that the tuner is busy and exit. > - Tested media device allocator API with bind/unbind testing on > snd-usb-audio and au0828 drivers to make sure /dev/mediaX is released > only when the last driver is unbound. > - Addressed review comments from Hans on the RFC v8 (rebased on 4.19) > - Updated change log to describe the use-case more clearly. > - No changes to 0001,0002 code since the v7 referenced below. > - 0003 is a new patch to enable ALSA defines that have been > disabled for kernel between 4.9 and 4.19. > - Minor merge conflict resolution in 0004. > - Added SPDX to new files. > > Changes since v9: > - Patch 1: Fix mutex assert warning from find_module() calls. This > code was written before the change to find_module() that requires > callers to hold module_mutex. I missed this during my testing on > 4.20-rc6. Hans Verkuil reported the problem. > - Patch 4: sound/usb: Initializes all the entities it can before > registering the device based on comments from Hans Verkuil > - Carried Reviewed-by tag from Takashi Iwai for the sound from v9. > - No changes to Patches 2 and 3. > > References: > https://lkml.org/lkml/2018/11/2/169 > https://www.mail-archive.com/linux-media@xxxxxxxxxxxxxxx/msg105854.html > > Shuah Khan (4): > media: Media Device Allocator API > media: change au0828 to use Media Device Allocator API > media: media.h: Enable ALSA MEDIA_INTF_T* interface types > sound/usb: Use Media Controller API to share media resources > > Documentation/media/kapi/mc-core.rst | 41 ++++ > drivers/media/Makefile | 4 + > drivers/media/media-dev-allocator.c | 144 +++++++++++ > drivers/media/usb/au0828/au0828-core.c | 12 +- > drivers/media/usb/au0828/au0828.h | 1 + > include/media/media-dev-allocator.h | 53 ++++ > include/uapi/linux/media.h | 25 +- > sound/usb/Kconfig | 4 + > sound/usb/Makefile | 2 + > sound/usb/card.c | 14 ++ > sound/usb/card.h | 3 + > sound/usb/media.c | 327 +++++++++++++++++++++++++ > sound/usb/media.h | 74 ++++++ > sound/usb/mixer.h | 3 + > sound/usb/pcm.c | 29 ++- > sound/usb/quirks-table.h | 1 + > sound/usb/stream.c | 2 + > sound/usb/usbaudio.h | 6 + > 18 files changed, 723 insertions(+), 22 deletions(-) > create mode 100644 drivers/media/media-dev-allocator.c > create mode 100644 include/media/media-dev-allocator.h > create mode 100644 sound/usb/media.c > create mode 100644 sound/usb/media.h > -- Kind regards, Sakari Ailus
